A pumping test in an aquifer has yielded the following data: A pumping well with a diameter of 15 cm pumps at a rate of 12 m³/day, and draws the aquifer down by 3.6 m. Drawdown at a monitoring well 20 m away is 1.1 m. a) Calculate the Transmissivity of the aquifer. Assume this number is representative of the entire aquifer. b) Determine saturated hydraulic conductivity, and identify a soil type from table 7.2 in the Margulis book. The aquifer thickness is 20 m.

A pumping test in an aquifer has yielded the following data: A pumping well with a diameter of 15 cm pumps at a rate of 12 m³/day, and draws the aquifer down by 3.6 m. Drawdown at a monitoring well 20 m away is 1.1 m. a) Calculate the Transmissivity of the aquifer. Assume this number is representative of the entire aquifer. b) Determine saturated hydraulic conductivity, and identify a soil type from table 7.2 in the Margulis book. The aquifer thickness is 20 m.

Principles of Geotechnical Engineering (MindTap Course List)

9th Edition

ISBN:9781305970939

Author:Braja M. Das, Khaled Sobhan

Publisher:Braja M. Das, Khaled Sobhan

Chapter7: Permeability

Section: Chapter Questions

Problem 7.22P: Refer to Figure 7.24. The following data were collected during the field permeability measurement of...

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The thickness of a horizontal, confined, homogeneous, isotropic aquifer of infinite areal extent is 30m. A well fully penetrating the aquifer was continuously pumped at a constant rate of 0.1 m³/s for a period of 1 day. The drawdowns given in the table below were observed in a fully penetrating well 90 m from the pumping well. Compute the transmissivity and the storativity by using: a) the Theis method of log-log matching. b) the Cooper-Jacob method of semi-log plotting. [For Part a), you have to first use attached Table to plot the values of W(u) versus 1/u on a log-log graph in the range of 10-9
2. A confined aquifer is recharged by a continuous supply of water from the certain source. The average thickness of the aquifer was determined to be 25 m and the average width is 4 km. The hydraulic conductivity of the aquifer was obtained at 40 m/day and its void ratio is 0.3333. The piezometer heads in two wells 1.325 km apart are 65 meters and 60 meters from a common reference datum. Determine the rate of flow in cubic meters per day. Determine: •compute the rate of flow through the aquifer in m3/day •compute the seepage velocity in m/day •compute the time of travel from the head of the aquifer to a point 8 km downstream in days
An unconfined aquifer is 10 m thick and is being pumped so that one observation well placed at a distance 76 m shows a drawdown of 0.5 m. On the opposite side of the extraction well is another observation well 100 m from the extraction well, shows a drawdown of 0.3 m. Assume the coefficient of permeability of 50 m/day. a.) What is the discharge f the extraction well? b.) Suppose the well at 100 m from the extraction well is now pumped. Show with a sketch what this will do to the drawdown. c.) Suppose the aquifer sits on an aquaclude that has a slope of 1/100. Show with a sketch what this will do to the drawdown.
A saturated aquifer sample core of diameter 2.54 cm and length of 6 cm weighs 63 grams. After drying the sample weighs 53 grams. The core sample was placed into an permeameter and exposed to a unit hydraulic gradient. The measured flowrate was 25.4 milliliters/second. The water levels in three wells in the same aquifer were measured in meters above MSL. The levels were: Well MW-1: 83.1 m; Well MW-2: 84.6 m; Well MW-3: 83.9 m. Well MW-2 is located 1km due north of Well MW-1, and Well MW-3 is located 700 meters Northeast of Well MW-1. Determine: 1. Estimate the porosity of the aquifer. 2. Estimate the hydraulic conductivity of the aquifer. 3. Sketch the relative positions of the three wells. Use MW-1 as the origin of the local (your sketch) coordinate system, and North is to the top of your sketch. 4. Determine the magniture and direction of the hydraulic gradient in the aquifer monitored by the three wells. Indicate the hydraulic gradient on your sketch (direction and magnitude) 5.…
4. A field sample of an unconfined aquifer is packed into a test cylinder. The length and diameter of the cylinder are 80cm and 20cm respectively. The field sample is tested for a period of 2 minutes under a constant head difference of 15 cm. As a result, 35 cm of water is collected at the outlet. a) Determine the hydraulic conductivity of the aquifer b) During those 2 minutes, how far would water have travelled in the test cylinder if effective porosity was measured as 35%?
9) A well is located in a confined aquifer near the intersection of a constant head and impervious boundary. a) Estimate the steady state drawdown in the well for Q=2 ft³ s, rw = 1 ft, distance from the well to stream= 300ft and distance from well to impervious boundary= 150 ft. T = 0.14ft²/s b) Estimate the steady state drawdown at point P located midway between the well and the steam. The angle between the stream and the impervious boundary is 90°
31 Yuri wants to determine the permeability of an aquifer. The aquifer has a test well 300-mm in diameter with two observation wells. A pumping test was conducted for 24 hours with the discharge being held constant at 5,721.4 m^3/day. The first one, 81.07 meters from the test well, has a draw-down of 0.6 meters. The second one, 40 meters from the test well, has a draw-down of 1.43 meters.The static water table penetrates the well to a depth of 25 meters. Determine the radius of influence of the aquifer in meters. Round off to three decimal places.
In using a permeameter, it is sometimes convenient to make a “falling -head” test. The horizontal tube is 1 m long and 10 cm in diameter and is filled with sample material. During a test, the upstream head h₁ falls from 200 to 180 cm in 4 hr, while h₂ is held constant at 15 cm. The diameter of the vertical tube in which h₁ is measured is 40 cm. What is the indicated average hydraulic conductivity? Estimate the range between maximum and minimum values of hydraulic conductivity.
A well in an aquifer is pumped over a long period at a rate of 0.05 m3 /s under approximate steady-state conditions. The steady-state drawdowns, from the water table level, at two observation wells at 25 m and 50 m from the abstraction well were observed to be 15.3m and 9.5m, respectively. If the saturated thickness of the aquifer prior to pumping is 80 m, determine the hydraulic conductivity of the aquifer material.
2. (a) A well in an aquifer is pumped over a long period at a rate of 0.05 m3 /s under approximate steady-state conditions. The steady-state drawdowns, from the water table level, at two observation wells at 25 m and 50 m from the abstraction well were observed to be 15.3m and 9.5m, respectively. If the saturated thickness of the aquifer prior to pumping is 80 m, determine the hydraulic conductivity of the aquifer material. (b) Will the actual drawdown in the pumping well be more than the theoretical drawdown? If yes, why and what measures can you recommend for reducing the drawdown in the pumping well?
Three piezometers have been installed in the confined aquifer shown in Figure 2 below. The aquifer has a uniform thickness of 3.5 m and a hydraulic conductivity of 2x10-1 cm/s. Determine the hydraulic gradient, the direction of flow, the transmissivity, and the flow rate per unit width of the aquifer.
QUESTION 12 1. A 40 cm well completely penetrates an unconfined aquifer of saturated depth 40 m. After a long period of pumping at a steady rate of 0.025 m³/s, the drawdown in two observation wells 20 m and 80 m from the pumping well were found to be 4.0 m and 2.0 m respectively. Determine the hydraulic conductivity of the aquifer. Round off to two (2) decimal places, Fill in the blank_ x 105 m/s